In the last year, 34 researchers have used the resources of the Laboratory of Cellular and Molecular Biology Microscopy Core. While most of the researchers come from the Laboratory of Cellular and Molecular Biology, the Core has been used by scientists from the Laboratory of Metabolism (Protein Section) and the Cell and Cancer Biology Branch. Almost all of the Principal Investigators in the Laboratory of Cellular and Molecular Biology have projects that involve the Core facility. Dr. Lawrence Samelson uses Core resources for the project "Biochemical Basis of T Cell Activation". Researchers working with Dr. Carol Clayberger have used the facility for the projects "Regulation of RANTES Expression in T Lymphocytes" and "Function of Granulysin". The Core has been involved with the project "Cbl Proteins as Regulators of Tyrosine Kinase Signaling"from Dr. Stanley Lipkowitz. Dr. Carole Parent's project, "Signaling Events Regulating Chemotaxis" uses all of the Core instruments. Dr. Paul Randazzo has made extensive use of the Core for the projects "Regulation of focal adhesions" and "Turnover of invadopodia". The Core facility has assisted Dr.Jeffry Rubin with the project "Secreted Frizzled-Related Proteins and Wnt Signaling". Dr. Ying Zhang uses Core instruments for the project "Molecular Mechanisms of TGF-beta Signaling Pathway". In addition, the Core facility has been used by personnel working with Principal Investigators from other groups including work with Dr. Michael Bustin on the nucleosome binding protein HMGN1 and the role of heterochromatin formation in cell migration. This research usually involves the use of a Zeiss 510 Laser Scanning Confocal Microscope or a PerkinElmer UltraView Spinning Disk Confocal Microscope. Most of the users view immunofluorescent staining on fixed samples with the Zeiss 501 LSCM while the sjpinning disk confocal is used for live cell imaging. We have started to use our Total Internal Reflection Fluorescence (TIRF) microscope for PhotoActivation Localization Microscopy (PALM). This high resolution technique will allow us to determine the location of single proteins clustered in signaling complexes in T cells with an accuracy of around 20 nm, well below the diffraction limit of visible light. The TIRF system is also being used for the projects "Regulation of focal adhesions" and "Turnover of invadopodia" with Dr. Paul Randazzo.